Dart guns are used to medicate or tranquilize an animal with a chemical substance or medication. The dart gun fires a dart or ballistic syringe that contains the chemical substance, and when a sharp tip portion or needle of the dart penetrates the skin of a animal, the chemical substance is injected into the animal. Typically, dart guns are used when handling or capturing the animal in a conscious state would be dangerous or difficult and time consuming.
The dart or ballistic syringe is typically generally cylindrical in shape and includes a central body portion for containing the chemical substance (medication or drug), a front needle for penetrating the skin and delivering the dose of medication or drug, and fletchings mounted to the rear end for stabilizing the dart while in flight. Typically, a steel ball, priming substance or pressurized valve is used in conjunction with the dart to cause the dose to be injected into the subject on impact, and sometimes the dart has other features that automatically remove the dart from the animal after administering the dose. In most cases, the dart is usually .50 caliber or 12.95 millimeters in diameter (typical diameter of a .50 caliber bullet or firearm cartridge). The guns used to fire the darts generally take the form of a rifle or long gun, pistol, crossbow or breath-powered blowgun.
Typically, in the rifle category, dart guns are either powered by compressed carbon dioxide (CO2) or exploding gunpowder (e.g., similar to standard firearm cartridges utilizing gunpowder to fire a bullet). For compressed CO2 powered rifles, a can or cartridge containing the compressed CO2 mounts to the rifle and provides a supply of pressurized gas to the barrel. When the trigger is pulled, a burst of gas shoots into the back of the barrel (behind the dart), generating a large amount of pressure and causing the dart to fire out of the barrel. In most cases, the amount of shots per a given cartridge will vary depending on several factors including the size of the cartridge, the amount of CO2 contained within the cartridge, and the ambient temperature of the air surrounding the cartridge. CO2 powered dart guns may not be favored in cold environments because of reduced operability. Also, CO2 powered dart guns may be disfavored because it is difficult or impossible to know when the next shot will fail due to insufficient pressurization when the cartridge runs out of gas, often resulting in waste of an expensive dose of medication in a lost or contaminated dart.
Rifles using exploding gunpowder as the propellant are generally in the form of a shotgun, for example, wherein a shot shell adapter (generally shaped like a traditional shotgun shell) is provided for firing the dart from the barrel. Typically, the shot shell adapter accepts a blank .22 caliber cartridge (offset from the center of the bore to allow the centered firing pin to strike the rim) and is loaded in the shotgun like a traditional break action shotgun. Depending on the particular location of the dart within the barrel (usually placed right in front of the shot shell adapter, or may be spaced a distance away by an extension rod extending therefrom), the explosion of the gunpowder within the shot shell adapter can cause damage to the fletchings of the dart, potentially affecting the flight of the dart and missing the target, which can be very costly where the dose is wasted due to injecting on impact. After firing the blank cartridge, the shell shot adapter is removed from the shotgun and the extension rod can be unscrewed and used to eject the used blank firing cartridge from the shot shell adapter, which is known to be a tedious and time consuming process. Additionally, and especially for large animals, loud noises are known to cause severe stress, and adding additional stress to large animals can potentially reduce their chances of surviving. Also, many countries' laws impose restrictions on sale and transport of firearms and ammunition, which can create difficulties in use of standard firearms adapted for use as a dart gun.
Accordingly, it can be seen that needs exist for an improved dart gun. It is to the provision of an improved dart gun meeting these and other needs that the present invention is primarily directed.